Hi,
Mathematica wil always use at least the machine precision and
it would not increase the speed when you use fewer digits, because
the arithmetic is done by the floating point hardware of your computer
and it would take more time to pass the two terms to the FPU, do the operation
and round the result to 3 digits, than to pass the terms and do the operation.
Regards
Jens
"Lee Newman" <leenewm at umich.edu> schrieb im
Newsbeitrag news:di59ru$3it$1 at smc.vnet.net...
| Dear Group,
|
| Situation
| - I have a large neural network model (my own
code, not Wolfram's
| toolbox) that currently has a run time of about
20hours.
| - I am in the process of trying to profile and
optimize the code
| (mostly matrix computations) to reduce the run
time.
| - All of the computationas that I do are
numerical.
|
| Questions
| (1) If I am not concerned about numerical
accuracy beyond 3 decimal
| places for any of the computations in the model,
can I improve
| performance by telling mathematica to globally
restrict its accuracy (or
| precision) for all computations?
|
| (2) If so, how do I do this? Is it as simple as
setting
| $MachinePrecision=3? Is there a global way
(rather than local use of
| N[]) to ensure that all computations are done
numerically, and with
| machine precision?
|
| Thanks,
| Lee Newman
|